The advent of the information age has seen an exponential growth in the accumulation and storage of data, and various types of devices have been developed to store data both or on-line usage as well as for archival purposes. In the early days of the computer, before the advent of magnetic disk and optical storage assemblies, data was typically stored on magnetic tapes, such as reel-to-reel tapes and later cassettes. In a magnetic tape transport apparatus, a magnetic coil is used as a transducer to imprint data magnetically on a moving band of magnetic film. Thereafter, when the film is advanced across the transducer, the data may be read and re-input into a processor. A typical data storage tape cartridge for use in a magnetic tape transport apparatus incorporates a housing having a base and a cover which may be secured in a number of ways including screws and sonic welding, and a tape reel assembly supported by the housing and incorporating a central hub about which the magnetic tape is wound. The housing itself is sized for insertion into a typical tape drive such that it may be used with a 5.25-inch form factor drive, a 3.5-inch form factor drive or other known sizes.
Magnetic tape has an advantage in that it is relatively low in cost and can be erased and rewritten many times. While other types of data storage media, such as optical disks and laser disks, have been developed in an effort to increase the density of stored data, magnetic tape remains a highly desirable format for archiving data in situations where the ability to radially access the data is of less significance, yet where cost remains a concern. Nonetheless, as the insatiable demand for data storage and retrieval grows, the magnetic tape industry has had to at least keep pace with advances in other types of data storage industries in order to remain competitive. For example, thinner bands of tape are being employed to optimize the surface area of media that may be stored within a given cartridge. Further, efforts are being made to record more data per unit area of the tape surface by increasing the number of tracks per unit width and the number of bytes per unit length. U.S. Pat. No. 6,078,478 issued Jun. 20, 2000 illustrates one approach which particularly concerns the controlled movement of a read/write head along a linear axis which may be used to increase the density of recorded data on a magnetic tape recording medium by increasing the plurality of tracks that are made on the medium. Other strides have been made for those tape drives which utilize air bearing technology to float recording tape on a thin cushion of air as it is translated across the read/write transducer of a tape transport apparatus. While a prevalent technology still found in many products such as the IBM 3480/3490/3590 family of tape drives, forces pressurized air through small drilled holes in the bearing surface, U.S. Pat. No. 5,777,823, issued Jul. 7, 1998 teaches an improved approach to air bearing technology which eliminates the disadvantages attendant with individually drilling ports through bearing surfaces
As industry demands increase, other advances will likely be made to improve the technology in this field. It has heretofore, however, not been known to significantly modify or otherwise alter the air filtration techniques employed in conjunction with tape drive apparatuses, particularly magnetic tape drive apparatuses which utilize air bearing technology. Such systems require filtration of the inlet air to prevent contamination from the operating environment. It is known to use an external air pump for the purpose of creating the air pressure and flow required to float the magnetic tape satisfactorily as it is translated through the drive across the read/write transducer between the data tape storage cartridge and a take-up reel. To provide adequate filtration, ambient air is typically drawn by the pump through an associated air filter before being pressurized and sent to the air bearing surfaces. However, due to the airflow rate requirements of larger form-factor tape drives, these rotary vane pumps are relatively large and expensive and they, as well as their associated filters, cannot be integrated into the space confinements of the tape drive. The result is a more bulky and expensive air filtration system, and these drawbacks have been exacerbated because the large and expensive rotary vane pumps traditionally employed will, for various reasons, become incompatible or inadequate with small form-factor tape drives that are the wave of the future. Further, since traditional rotary vane pumps have internal filters, which are used many times during use of the tape transport apparatus, a proper maintenance schedule entails the need to periodically replace these filters to help prolong operability of the tape transport apparatus as well as integrity of magnetic tape media.
Ideally, then, it is desirable to design a system which not only provides adequately filtered air to guide the band of tape medium across the air bearing surface while preventing contamination from the operating environment, but to also minimize the size, power and cost of the air pump associated with such air filtration systems. Accordingly, despite the various advances made in other aspects of magnetic tape transport apparatuses, there remains a need for addressing the air filtration side of the technology to keep pace with both and future demands of the industry. It has surprisingly been found that modifications can be made to conventional magnetic tape storage cartridges to fulfill these needs.